Liquid proving systems utilizing a bottom drain liquid prover that drains into a liquid holding tank can be used to prove the accuracy of the reading displayed on a liquid dispensing pump. U.S. Pat. No. 7,874,195 (to Murnane, Jr.; also Canadian Patent No. 2,626,280) and U.S. Patent Application Publication No. 2012/0137750 (to Murnane, Jr. et al.; also Canadian Patent No. 2,727,049) describe the art of proving systems that can be used, in particular, to prove gasoline and diesel pumps at filling (gas) stations (or gas bars) where top-fill and bottom-drain provers are used. Top-fill and bottom-drain provers (test measures) are conveniently used in these small volume applications (typically five gallons (20 liters) or less) since existing standards and convention dictate use of such provers. Combined top-fill or bottom-fill and bottom drain provers are limited in use in known proving systems to large volume meter applications, such as metered filling of gasoline tanker trucks, where a single proving measurement is performed, after which the large volume combined top-fill or bottom-fill and bottom-drain prover is emptied back into the tank from which the liquid was drawn. These combined top-fill or bottom-fill provers typically range in capacity from 500 gallons (1,500 liters) to 1,500 gallons (5,000 liters). Such large volume single proving measurement applications are contrasted with existing small volume top-fill and bottom-drain applications that drain to a directly connected liquid holding tank so that multiple proving measurements can be performed before the liquid holding tank must be emptied back into the tank from which the liquid was drawn.
Illustrated in FIG. 1(a) is known liquid prover system 101. Bottom drain prover 100 is installed near a front end of liquid holding tank 200 with the interior of the prover's drain section 100c connected to the interior of liquid holding tank 200 via drain valve 100d. Bottom drain prover 100 typically has a narrow upper neck 100a with fill opening 100a′ for filling the prover with liquid from the liquid dispensing pump, a wider diameter body section 100b for accumulating and holding the bulk of the liquid pumped into the prover, and a narrow drain section 100c with a drain opening. Drain valve 100d is provided for controlling release of the accumulated liquid from the prover via drain valve lever mechanism 100d′ (shown in FIG. 1(b)). The prover's volume gauge or indicator can be a gauge glass tube 100e that has its interior volume connected to the interior volume of neck 100a. The gauge glass is marked along its height with a neck scale that reflects the capacity of liquid in the above prover when drain valve 100d is closed and the prover is filled with liquid up to the neck region of the prover. The nominal capacity of the prover, and deviations therefrom, are marked on the scale using standards that are established by the applicable standards organizations. Use of the prover is as disclosed in U.S. Pat. No. 7,874,195. Vapor conduit 400 connects the interior volumes of neck 100a and tank 200 so as to form a closed path for vapors in prover 100 and tank 200. The combination of nozzle sealing gasket 900 and nozzle removed self seal assembly 320 minimizes the release of vapors from top-fill opening 100a′ regardless of whether or not the dispensing pump's nozzle is inserted into the fill opening. Ambient air vent 420 allows ambient (atmospheric) pressure equalization in the liquid holding tank as the tank is filled with liquid drained from the prover, and emptied via the tank's discharge line 200a and discharge control valve 200b. 
FIG. 1(b) illustrates three of the liquid prover systems shown in FIG. 1(a) connected to common support structure 920.
FIG. 3(a) illustrates nozzle removed self seal assembly 320 used with the prover system shown in FIG. 1(a). The nozzle removed self seal assembly comprises sealing plate 340 (FIG. 4), which is in the shape of an annular disk with an annulus or through opening 340a, and through opening self sealing assembly 360 (FIG. 5 with sealing plate 340 shown in dashed lines), which opens when a dispensing pump's nozzle is inserted in the through opening and closes when the nozzle is withdrawn from the through opening. The diameter of the through opening is identified as “d” in FIG. 3(a). Generally through opening 340a is limited in size to the outer dimension of the nozzle to be inserted into the through opening with additional clearance as required for nozzle insertion into the through opening.
In FIG. 3(a), nozzle sealing gasket 900 is seated adjacently above nozzle removed self seal assembly 320 to form a combination prover fill opening self sealing assembly wherein the nozzle sealing gasket 900 primarily prevents release of vapors through the fill opening when a nozzle is inserted in opening 900a in gasket 900, and closed flapper door 360a in the nozzle removed self seal assembly 320 prevents release of vapors through the fill opening when a nozzle is not inserted through opening 340a in sealing plate 340. Nozzle sealing gasket 900 has opening 900a, which is sufficiently large in cross section (shown as diameter “d1” in FIG. 3(a)) to push a nozzle through while substantially maintaining a vapor seal between the perimeter of opening 900a and the exterior section of the nozzle pushed through opening 900a. As shown in FIG. 3(b), alternative nozzle sealing gasket 900′ may be of an annular ring shape and positioned within through opening 340a as shown in FIG. 3(a).
FIG. 5 illustrates through opening self sealing assembly 360 that can be used with the prover system shown in FIG. 1(a). The through opening self assembly comprises flapper door 360a, self-closing spring loaded hinge 360b, and shim 360c as shown in FIG. 6(a), FIG. 6(b) and FIG. 6(c), respectively. Flapper door 360a is located on the side of sealing plate 340 that faces the interior of the prover's neck volume, and positioned so that the flapper door is seated over the entire through opening 340a when a nozzle is not positioned in the through opening, thus providing a seal to prevent release of vapors through the fill opening to atmosphere. Flapper door 360a is attached to first wing 360b′ of self-closing spring loaded hinge 360b while the second wing 360b″ is suitably attached to shim 360c, which, in turn, is suitably attached to sealing plate 340 as seen in FIG. 3(a). The first and second wings are suitably connected to spring 370 of the self-closing spring loaded hinge. Therefore the flapper door ensures that vapors are not released from the neck of prover 100 to atmosphere unless a dispensing pump's nozzle is inserted into the sealing plate's through opening 340a. Inserting the nozzle into the through opening will force the spring loaded flapper door to open against the inserted nozzle. Preferably the diameter of through opening 340a is sufficiently large enough to allow easy passage of the nozzle, or a range of nozzles, intended to be used with the prover, without excess release of vapors though any clearance space between the through opening and the outer diameter of the nozzle.
The combination of nozzle sealing gasket 900 and nozzle removed self seal assembly 320 minimizes the release of vapors from fill opening 100a′ regardless of whether the dispensing pump's nozzle is inserted into the fill opening.
Ambient air vent 420 (FIG. 1(a) and FIG. 1(b)) is generally located near the (rear) end of liquid holding tank 200 that is opposite the (front) end near where prover 100 is located.
As illustrated in FIG. 1(a), FIG. 2(a) and FIG. 2(b) breather cap assembly 300 can be disposed over nozzle sealing gasket 900 and nozzle removed self seal assembly 320 when prover 100 is not being used for extended periods, for example, when the prover is being transported between gas stations. As seen in FIG. 2(c) through 2(e), through opening 900a in nozzle sealing gasket 900 is smaller than the through openings 300a′ and 100f′ in bayonet flange 300a and prover's neck flange 100f. Further opening 900a is sized to form a tight fit around the exterior of a pump's nozzle that is inserted through the opening. Typical nozzle sealing gasket 900 comprises a flexible material, such as a rubber composition, at least around through opening 900a so that the gasket seals around the nozzle inserted through opening 900a. 
Liquid prover system 101 as described above and in U.S. Pat. No. 7,874,195 results in an improved accuracy particularly when the liquid is highly volatile. It is an object of the present invention to provide a liquid prover with an improved vapor elimination system that results in greater accuracy than that of the liquid proving system described above when the bottom-drain prover is connected to a liquid holding tank.
It is another object of the present invention to provide a liquid proving system with a selectable top-fill or bottom-fill and bottom-drain prover that can be used in small volume proving applications.
It is another object of the present invention to provide a liquid proving system with a bottom-fill and bottom-drain prover that can be used in small volume proving applications.
It is another object of the present invention to provide a liquid proving system with a top-fill and bottom-drain prover that can be used in small volume proving applications.
It is another object of the present invention to provide a nozzle adapter assembly that can be used with nozzles, including automatic shut-off nozzles, that are used with liquid dispensing pumps.